The present invention relates to floating dock systems that are resistent to wind damage or storm surge commonly associated with intense storm systems, in particular, hurricanes. If it is possible to submerse a dock system as a hurricane or other powerful storm approaches a coastal area, then the dock system will be below the water and not subject to wind damage caused by hurricanes force winds. Moreover, the storm surge and wave action associated with a hurricane or such similar intense storm system will have any, if any, effect on a dock system that is below the water surface at the time the storm surge and storm waves are hitting the coastal area where the dock system is located.
In coastal areas throughout the Southeastern United States, private piers and docks are common. Also, small private marinas using floating docks are often a feature associated with a waterfront housing development. Frequently, these types of docks are constructed relatively inexpensively. Wooden docks are attached to vertical wooden pilings sunk in the ground underneath the water. There are several requirements for these types of structures.
First, there must be access from the land to the structure. This ordinarily may be a pivoting walkway located on a bulkhead or on a pier structure that is significantly above the mean high tide level. The pivoting walkway is attached to or rests upon a floating dock. Ordinarily, this floating dock is made of treated wood, which is resistent to rain, salt spray, and so forth. The floating dock ordinarily is supported on hollow barrels or similar structures. These floatation devices may be filled with air or foam. The docks that are floated on these devices are ordinarily attached to wooden pilings, oftentimes by metal rings that extend around the pilings to allow vertical movement for the floating dock as the water rises and falls but secures the dock from floating off on the tide or other currents. This type of dock system works very well under most circumstances and under most weather conditions.
However, the Southeastern coast is particularly subject to hurricanes. Among other notable hurricanes in the last 10 years have been Hurricane Hugo, Hurricane Andrew, Hurricane Fran, and Hurricane Floyd. Many home owners have discovered that while their homes may be secure against the action of the wind and water, their docks and piers are not. A six or eight foot storm surge, common to hurricanes, can lift a floating structure entirely above hence, off the pilings. Once disconnected from the pilings, the floating docks become like a boat or other floatable object that has come loose from its moorings. It is subject to damage from impact against solid fixed objects, and in turn it can damage bulkheads, boats, piers, and whatever structure may be in the way of a floating dock as it is being moved about by wind and wave action during a hurricane.
This result is undesirable for two reasons. First, docks, pilings, and piers are themselves expensive and, if damaged or destroyed in a hurricane, costly to replace. Second, a floating dock that has broken loose from its connection to pilings or to a pier is a dangerous object which is likely to damage boats or other nearby structures, even the home of the owner of the dock.
Submersible dock systems have been recognized as desirable for a variety of reasons. In some circumstances, it may be useful to first submerse a dock structure than to raise an object floated onto the dock structure. For example in Hindlin U.S. Pat. No. 3,626,447 a portable dry dock is disclosed which has inflatable pontoons. They are rail guides on the dock. A boat or ship is maneuvered between the markers on the side of the platform, pontoons are inflated which float the platform and raise the vessel on the floating dry dock. Boudrias U.S. Pat. No. 4,938,629 discloses a floatable wharf structure made of concrete modules. The modules have an inner chamber with plugs that are removed to allow water to enter the chamber as air is removed from the chamber by another aperture. The shell is re-floated by reversing the air circulation. Medlrum U.S. Pat. No. 5,106,237 discloses a submersible dock system designed to be submerged to avoid damage from ice. This is a galvanized metal system heavier than the water on which it is placed. It is raised and lowered mechanically, rather than relying on a floatation system to maintain a portion of the system above water. The purpose of this invention is to allow the entire dock system to be submerged to avoid ice related damage to the structure.
Despite these inventions, there still remains a need for a simply constructed and relatively inexpensive apparatus whereby a dock system may be submerged beneath the water in the event of an approaching violent storm system which promises to have damaging wind, damaging wave action, and a large storm surge.
The current invention is adapted for use with a floating dock supported by floatation chambers. The floatation chambers are hollow. In this invention, each chamber will have at least one valve for introduction or evacuation of air and for introduction or evacuation of water. As pressurized air is added to the chamber, water is forced from the chamber by the incoming air. As air is evacuated from the chamber, water fills the chamber. When all the air is evacuated from the chamber and the chamber is filled with water, then the floatation chamber will provide little, if any, floatation for the floating dock. If necessary, appropriate ballast, added to the dock, means that the combined weight of the dock, of the floatation chamber filled with water, and of the ballast will be greater than the water displaced, hence, the dock will sink. The dock will settle to the bottom but is still connected to pilings. Because the dock is below the water level, changes in the water level from storm surges and waves will have little, if any, effect on the dock.
Thus, an owner of a floating dock having the current system will, as part of hurricane or storm preparation, simply sink his dock below the water level. When the storm has passed and it is safe, air will be reintroduced to the floatation chambers and water evacuated from the chambers. This will increase the buoyancy of the dock to where the water displaced by the dock system weighs more than the dock and the dock will float back above the water level.
Most docks will be sunk, at most, a few days before a storm approaches. Once the storm has passed, the dock will be re-floated. The docks will not be submerged below the water for an extended period of time. Hence, there will be little chance of damage from marine organisms, sea water, or other issues that could arise should the docks be submerged for long periods.